Illustrative embodiments pertain to the art of turbomachinery, and specifically to turbine rotor components.
Gas turbine engines are rotary-type combustion turbine engines built around a power core made up of a compressor, combustor and turbine, arranged in flow series with an upstream inlet and downstream exhaust. The compressor compresses air from the inlet, which is mixed with fuel in the combustor and ignited to generate hot combustion gas. The turbine extracts energy from the expanding combustion gas, and drives the compressor via a common shaft. Energy is delivered in the form of rotational energy in the shaft, reactive thrust from the exhaust, or both.
The individual compressor and turbine sections in each spool are subdivided into a number of stages, which are formed of alternating rows of rotor blade and stator vane airfoils. The airfoils are shaped to turn, accelerate and compress the working fluid flow, or to generate lift for conversion to rotational energy in the turbine.
Airfoils may incorporate various cooling cavities located adjacent external side walls. Cooling air, depending on the airfoil configuration (e.g., blade, vane, etc.) may be supplied from an inner diameter and/or an outer diameter thereof. For example, typically blades are fed cooling air through a platform at an inner diameter thereof. Vanes, however, may be fed cooling air from one or both of the inner and outer diameters. In some arrangements, the platforms of the airfoils may be configured with platform cover plates with impingement holes. The cover plates having impingement holes may be arranged to direct cooling air onto the non-gaspath surfaces of the platform itself, to thus cool the platform.
The cool air may pass through the impingement holes of the cover plate, impinge upon the platform, and then flow into one or more cooling cavities of the airfoil. Such cooling cavities are subject to both hot material walls (exterior or external) and cold material walls (interior or internal). Although such cavities are designed for cooling portions of airfoil bodies, various cooling flow characteristics can cause hot sections where cooling may not be sufficient. Accordingly, improved means for providing cooling within an airfoil may be desirable.